Child maltreatment affects 1 in 5 children nationwide and often leads to profound childhood physical, psychological, and behavioral consequences, which may persist throughout the life course. Interventions to prevent maltreatment are critically needed: besides the inestimable cost in human suffering, maltreatment's material costs to society total over $100 billion per year. Though most prevention efforts focus on individuals or families, the neighborhood is a key environment that both influences maltreatment rates and that might serve as a potential intervention target to reduce maltreatment. Our mixed-methods study in Cleveland, OH and research elsewhere found that neighborhood structural factors (economic disadvantage, residential instability, childcare burden, immigrant concentration) are linked to greater maltreatment, even after accounting for the effects of family and individual factors. Paradoxically, since our study 20 years ago, Cleveland's poverty rate has raised, yet neighborhood maltreatment rates have varied widely: Many of these rates have decreased, some sharply, some only slightly, while others have increased. Why? Our study will identify how possible differences over time in neighborhood ecologies may contribute: (1) differences in neighborhood conditions as reflected by structural factors and concomitant changes in neighborhood social processes and dis-amenities (undesirable conditions such as blight, crime); (2) differences in the organization and provision of social services, resources in which Cleveland invested significantly since the initial study; and (3) differences in professionals' (mandated) an non-professionals' (non-mandated) definition, reporting, and substantiation of maltreatment. Our underlying hypothesis is that the effects of structural factors and dis-amenities on maltreatment have changed over time because of the moderating influence of services, as well as changes in definition/reporting practices that result in variable substantiation rates. To achieve our study purpose, we propose a comprehensive, nested, mixed-methods investigation, conducting both a citywide panel study, as well as an in-depth investigation of 20 neighborhoods, where complimentary qualitative and quantitative data will be collected and analyzed jointly for a more complete understanding of the 3 pathways. We have a rich store of quantitative and qualitative data reaching back up to 20 years on neighborhood conditions, services, and definition/reporting; this is a unique resource to reveal these pathways' roles in influencing maltreatment over time. The proposed study is innovative: it will compare and contrast neighborhood conditions, services, and definition/reporting over a 20-year period. The study is highly significant: experts nationwide are unsure of the forces shaping US maltreatment rates, forces which this study will address. The study has significant potential to shape child welfare policy by identifying specific neighborhood conditions, service elements, and definition/reporting practices linked to reduced maltreatment rates. Moreover, because conditions in Cleveland mirror those of many urban areas nationwide, expected results will be relevant to numerous US cities.